diff --git a/hub/common.py b/hub/common.py
index fc147a2..31c9c1a 100644
--- a/hub/common.py
+++ b/hub/common.py
@@ -5,6 +5,7 @@ import hmac
 import ipaddress
 import logging
 import logging.handlers
+import socket
 import typing
 import collections
 from bisect import insort_right
@@ -153,6 +154,38 @@ def protocol_version(client_req, min_tuple, max_tuple):
     return result, client_min
 
 
+async def resolve_host(url: str, port: int, proto: str,
+                       family: int = socket.AF_INET, all_results: bool = False) \
+        -> typing.Union[str, typing.List[str]]:
+    if proto not in ['udp', 'tcp']:
+        raise Exception("invalid protocol")
+    try:
+        if ipaddress.ip_address(url):
+            return [url] if all_results else url
+    except ValueError:
+        pass
+    loop = asyncio.get_running_loop()
+    records = await loop.getaddrinfo(
+        url, port,
+        proto=socket.IPPROTO_TCP if proto == 'tcp' else socket.IPPROTO_UDP,
+        type=socket.SOCK_STREAM if proto == 'tcp' else socket.SOCK_DGRAM,
+        family=family,
+    )
+    def addr_not_ipv4_mapped(rec):
+        _, _, _, _, sockaddr = rec
+        ipaddr = ipaddress.ip_address(sockaddr[0])
+        return ipaddr.version != 6 or not ipaddr.ipv4_mapped
+    records = filter(addr_not_ipv4_mapped, records)
+    results = [sockaddr[0] for fam, type, prot, canonname, sockaddr in records]
+    if not results and not all_results:
+        raise socket.gaierror(
+            socket.EAI_ADDRFAMILY,
+            'The specified network host does not have any network '
+            'addresses in the requested address family'
+        )
+    return results if all_results else results[0]
+
+
 class LRUCacheWithMetrics:
     __slots__ = [
         'capacity',
@@ -577,10 +610,10 @@ IPV4_TO_6_RELAY_SUBNET = ipaddress.ip_network('192.88.99.0/24')
 def is_valid_public_ipv4(address, allow_localhost: bool = False, allow_lan: bool = False):
     try:
         parsed_ip = ipaddress.ip_address(address)
-        if parsed_ip.is_loopback and allow_localhost:
-            return True
-        if allow_lan and parsed_ip.is_private:
-            return True
+        if parsed_ip.is_loopback:
+            return allow_localhost
+        if parsed_ip.is_private:
+            return allow_lan
         if any((parsed_ip.version != 4, parsed_ip.is_unspecified, parsed_ip.is_link_local, parsed_ip.is_loopback,
                 parsed_ip.is_multicast, parsed_ip.is_reserved, parsed_ip.is_private)):
             return False
@@ -593,12 +626,14 @@ def is_valid_public_ipv4(address, allow_localhost: bool = False, allow_lan: bool
 def is_valid_public_ipv6(address, allow_localhost: bool = False, allow_lan: bool = False):
     try:
         parsed_ip = ipaddress.ip_address(address)
-        if parsed_ip.is_loopback and allow_localhost:
-            return True
-        if allow_lan and parsed_ip.is_private:
-            return True
-        return not any((parsed_ip.version != 6, parsed_ip.is_unspecified, parsed_ip.is_link_local, parsed_ip.is_loopback,
-                        parsed_ip.is_multicast, parsed_ip.is_reserved, parsed_ip.is_private))
+        if parsed_ip.is_loopback:
+            return allow_localhost
+        if parsed_ip.is_private:
+            return allow_lan
+        return not any((parsed_ip.version != 6, parsed_ip.is_unspecified,
+                        parsed_ip.is_link_local, parsed_ip.is_loopback,
+                        parsed_ip.is_multicast, parsed_ip.is_reserved,
+                        parsed_ip.is_private, parsed_ip.ipv4_mapped))
     except (ipaddress.AddressValueError, ValueError):
         return False